The invention concerns a device for controlling an electric motor-actuated linear drive in the form of a furniture drive for adjusting moveably mounted parts of lying and seating furniture, comprising at least one threaded spindle drivable by way of a worm gear transmission for displacement of a respective stroke element, a guide body which is non-rotatably arranged on the respective threaded spindle and on which a worm gear is rotatably mounted, a coupling sleeve which is mounted non-rotatably but axially displaceably on the respective guide body and with which the worm gear and the guide body can be selectively connected or separated by means of a claw coupling, a respective actuating element serving for displacement of the coupling sleeves and a shift mechanism for driving the respective actuating element.
In a known electric motor-actuated furniture drive of the specified kind (EP 0 968 675 B1) the coupling sleeves are displaced by means of actuating pins to couple the threaded spindles to the worm gears and to uncouple them therefrom. The movement of the actuating pins is produced either by means of hand levers or by Bowden cables. The coupling halves which are moveable relative to each other in the axial direction of the threaded spindles are in that case moved at a relatively slow speed, that is to say the face tooth arrangements or claws of the claw coupling are separated from each other only slowly upon disconnection of the coupling and are moved gradually towards each other again when coupling is implemented. In the operating conditions in which the coupling is “almost uncoupled” and “almost coupled” those slow movements of the coupling halves lead to heavy loadings on the tooth arrangements because coupling shift is effected under load or while torque is being transmitted. In the case of that shift mechanism, that can result in severe wear of the coupling elements. In normal use that admittedly plays only a minor part, especially as the wearing parts can be so designed that they have the same service life as the corresponding articles of furniture. If however the furniture parts have to be very frequently adjusted, like for example in the hospital or care sector, then the wear of the coupling parts can under some circumstances have a detrimental effect.